The present invention relates generally to temperature indicators, and more particularly, to an apparatus and method to independently extend and retract a pair of temperature indictor sticks.
Temperature indicators are well known in the welding, metal fabrication, and heat treatment industries. Such products are capable of determining surface temperatures during welding and metal fabrication processes. The products have also found use in heat-treatment processes, and can determine operating temperatures of mechanical, hydraulic, and electrical systems and components, such as transformers and motors.
Initially, temperature sensing was conducted by sprinkling a few granules of a known compound on an object. When the granules melted, the desired temperature was achieved. Later, pellets were introduced to make marks similar to a chalk mark on a surface of the object rather than observing the entire pellet melt. Further improvements led from a pellet to a chalk stick, which is protected in a housing that includes an adjustable holder for positioning the temperature indicator stick relative to the housing.
One known temperature indicator includes a housing having a rimmed end and a flanged end. A temperature indicator stick is inserted into the housing through the flanged end and prevented from leaving the housing by the rimmed end. The stick also has an outer casing or holder that is threaded into the housing and encloses the flanges. The outer casing is tapered to constrict the flanges and lock the temperature indicator stick in a fixed position.
Problems exist with the current state of the art of temperature indicators. Existing holders for temperature indicators are not satisfactory. Such holders are often limited in their ability to fix the temperature indicator stick in position. Operator use of the temperature indicator stick results in pressure exerted on the end of the stick during marking which causes the stick to retract into the housing. Generally, the operator must unscrew the outer casing, reposition the temperature indicator stick, and then retighten the outer casing to continue marking objects. Another problem is that current temperature indicators are configured to hold one temperature indicator stick, limiting temperature detection to a single temperature value. Operators desiring to detect several temperatures must carry or locate multiple temperature indicators, which is often tedious.
There is a need for an apparatus and method capable of separately fixing a pair of temperature indicator sticks in position during the marking of objects for temperature detection to reduce the number of temperature indicators used by operators. It would therefore be desirable to have a more efficient temperature indicator than current indicators by having a pair of temperature indicator sticks within a housing such that a pair of collets having threads engage each temperature indicator stick independently.